Convert to Latin Numbers

by codepo8

HTML

<input type="number">
  <output></output>

CSS

output {
  display: block;
  padding: 10px;
  font-size: 100px;
}

JavaScript

var output = document.querySelector('output');
var input = document.querySelector('input');
input.addEventListener('keyup', function(ev){
output.innerHTML = (new Array(+input.value+1))
  .join('I')
  .replace(/I{5}/g, 'V')
  .replace(/VV/g, 'X')
  .replace(/X{5}/g, 'L')
  .replace(/LL/g, 'C')
  .replace(/C{5}/g, 'D')
  .replace(/DD/g, 'M')
  .replace(/CCCC/, 'CD')
  .replace(/DCD/, 'CM')
  .replace(/XXXX/, 'XL')
  .replace(/LXL/, 'XC')
  .replace(/IIII/, 'IV')
  .replace(/VIV/, 'IX');
}, false);